The application relates generally to methods and apparatus for in-process form checks of manufactured components, and more specifically to checks of gas turbine airfoils.
Components, including those built to tight tolerances like airfoils, are repeatedly checked throughout the manufacturing process for conformance with such tolerances. For example, fan blades include several manufacturing stages such as casting or forging, quenching, rough machining, and final machining. Hollow fan blades include additional manufacturing steps depending on the chosen process for forming the internal features. Diffusion bonded hollow blades are formed in two pieces then joined around the edges. Both position and thickness of the blade surfaces must be measured often.
Tight tolerances often require expensive, high precision sensors which must consistently be placed correctly relative to the airfoil to reliably take correct measurements. The location of each measurement reading must also be correctly mapped to the corresponding airfoil reference point. Manual measurements using a single sensor without the aid of precise guidance can lead to significant opportunity for error both in position and location. One method of overcoming these shortcomings involves individual sensors fixed and integrated into a gauge at each and every reference point. However, such an arrangement is incredibly expensive, requiring the use of twenty or more sensors in order to take the simultaneous measurements.